| 摘要 |
<p>A moulding in thermoplastics such as polyalkenes, and a connecting piece in particular for thermoplastic tubes, is produced with a thick wall which has on each surface a skin of the same material as its inner core but with finer crystalline structure, the skin being rigid and sealed. Polymer is injection moulded with low viscosity and at high injection speed, first, further injection is carried out at low speed and pressure, and, in a third phase, while the polymer starts to cool, low viscosity material is injected at higher pressure. The equipment used as a heated injector. In the first, high-speed injection phase no polymer orientation takes place. The mould tools have thin inner liners with adjacent cooling bores for rapid action. After initial cooling, the moulding formed can be ejected e.g. together with the core tool and immersed in coolant until the core of the moulding has sufficiently cooled.</p> |
